The present invention pertains to compounds of the following formula: (1) wherein: R.sup.ALK is primary or secondary aliphatic saturated C.sub.2-6alkyl; each of R.sup.B2, R.sup.B3, R.sup.B4, and R.sup.B5 is independently --H, --OH, or --OMe; each of R.sup.1 and R.sup.2 is independently: --H, optionally substituted C.sub.1-4alkyl, or optionally substituted C.sub.5-20aryl; R.sup.A3 is --H, --OH, --OC(.dbd.O)R.sup.E, --OS(.dbd.O).sub.2OH, or --OP(.dbd.O)(OH).sub.2; R.sup.E is: --H, optionally substituted C.sub.1-6alkyl, optionally substituted C.sub.3-20heterocyclyl, or optionally substituted C.sub.5-20aryl; or a pharmaceutically acceptable salt, solvate, amide, ester, ether, chemically protected form, or prodrug thereof. The present invention also pertains to pharmaceutical compositions comprising such compounds, and the use of such compounds and compositions, both in vitro and in vivo, for both diagnosis and treatment of, for example, proliferative conditions, such as cancer, and inflammatory conditions ##STR00001##