Abstract: A method for modulating a Fer mediated pathway in a cell, for monitoring the effect of a Fer protein in a cell, for altering and inhibiting one or more effects of a Fer protein in a cell is provided. The method includes modulating, monitoring, altering or inhibiting any one or more or of the association of the Fer protein to PP1; the phosphorylation of PP1, the phosphatase activity of PP1, and the tumor suppressive activity of the retinoblastoma protein (RB). In a preferred embodiment, modulating a Fer mediated pathway in a cell, monitoring the effect of a Fer protein in a cell, for altering and inhibiting one or more effects of a Fer protein in a cell involves administrating to a cell a compound having a molecular weight of up to 1000 Dalton capable of modulating, altering or inhibiting an effect of Fer. Further provided is a method for determining whether a substance is capable of altering or inhibiting an effect of a Fer protein in a cell.